n-type absorber by Cd2+ doping achieves high-performance carbon-based CsPbIBr2 perovskite solar cells

A review: strategies for reducing the open-circuit voltage loss of wide-bandgap perovskite solar cells

Perovskite-based tandem solar cells (PTSCs) have made remarkable achievements in recent years, and the highest certified power conversion efficiency (PCE) of 33.9% has been achieved in perovskite/silicon tandem solar cells (PSTSCs), indicating their great commercialization potential. Nevertheless, the performance of PTSCs continues to be hindered by the compromised performance of wide-bandgap perovskite solar cells (WPSCs), particularly the high VOC deficit of WPSCs. Therefore, numerous strategies have been developed to minimize the VOC loss of WPSCs. Herein, we sort to comprehensively review about the reported studies on reducing the VOC deficit of WPSCs, focusing on interface modification, charge transport material (CTM) exploration, and additive engineering, with the aim of providing guidelines for increasing the VOC of WPSCs. Finally, we will provide a conclusive outlook on WPSCs, sharing our perspectives to inspire further advancements in both WPSCs and PTSCs.

Limitations and Progresses in Carbon-Based Cesium Lead Halide Perovskite Solar Cells

Inorganic cesium lead halide perovskites (CsPbIxBr3-x, 0≤x≤3) are promising alternatives with great thermal stability. Additionally, the choice of moisture-resistive and dopant-free carbon as the electrode material can simultaneously solve the problems of stability and cost. Therefore, carbon electrode-based inorganic PSCs (C-IPSCs) represent a promising candidate for commercialization, yet both the efficiencies and stability of related devices demand further progress. This article reviews the recent advancement of C-IPSCs and then unravels the distinctive merits and limitations in this field. Subsequently, our perspective on various modification strategies is analyzed on a methodological level. Finally, this article outlooks the promising research contents and the remaining unresolved issues in this field. We believe that understanding and analyzing the related problems in this field are instructive to stimulate the future development of C-IPSCs.

Surface Passivation by Sulfur-Based 2D (TEA)2PbI4 for Stable and Efficient Perovskite Solar Cells

Perovskite solar cells (PSCs) with superior performance have been recognized as a potential candidate in photovoltaic technologies. However, defects in the active perovskite layer induce nonradiative recombination which restricts the performance and stability of PSCs. The construction of a thiophene-based 2D structure is one of the significant approaches for surface passivation of hybrid PSCs that may combine the benefits of the stability of 2D perovskite with the high performance of three-dimensional (3D) perovskite. Here, a sulfur-rich spacer cation 2-thiopheneethylamine iodide (TEAI) is synthesized as a passivation agent for the construction of a three-dimensional/two-dimensional (3D/2D) perovskite bilayer structure. TEAI-treated PSCs possess a much higher efficiency (20.06%) compared to the 3D perovskite (MA_0.9FA_0.1PbI₃) devices (17.42%). Time-resolved photoluminescence and femtosecond transient absorption spectroscopy are employed to investigate the effect of surface passivation on the charge carrier dynamics of the 3D perovskite. Additionally, the stability test of TEAI-treated perovskite devices reveals significant improvement in humid (RH ∼ 46%) and thermal stability as the sulfur-based 2D (TEA)₂PbI₄ material self-assembles on the 3D surface, making the perovskite surface hydrophobic. Our findings provide a reliable approach to improve device stability and performance successively, paving the way for industrialization of PSCs.

High-Efficiency Carbon-based CsPbI2 Br Perovskite Solar Cells from Dual Direction Thermal Diffusion Treatment with Cadmium Halides

In recent years, carbon-based CsPbI₂ Br perovskite solar cells (PSCs) have attracted more attention due to their low cost and good stability. However, the power conversion efficiency (PCE) of carbon-based CsPbI₂ Br PSCs is still no more than 16%, because of the defects in CsPbI₂ Br or at the interface with the electron transport layer (ETL), as well as the energy level mismatch, which lead to the loss of energy, thus limiting PCE values. Herein, a series of cadmium halides are introduced, including CdCl₂ , CdBr₂ and CdI₂ for dual direction thermal diffusion treatment. Some Cd²⁺ ions thermally diffuse downward to passivate the defects inside or on the surface of SnO₂ ETL. Meanwhile, the energy level structure of SnO₂ ETL is adjusted, which is in favor of the transfer of electron carriers and blocking holes. On the other hand, part of Cd²⁺ and Cl^- ions thermally diffuse upward into the CsPbI₂ Br lattice to passivate crystal defects. Through dual direction thermal diffusion treatment by CdCl₂ , CdI₂ and CdBr₂ , the performance of devices has been significantly improved, and their PCE has been increased from 13.01% of the original device to 14.47%, 14.31%, and 13.46%, respectively. According to existing reports, 14.47% is one of the highest PCE of carbon-based CsPbI₂ Br PSCs with SnO₂ ETLs.

Monovalent Copper Cation Doping Enables High-Performance CsPbIBr2-Based All-Inorganic Perovskite Solar Cells

Organic-inorganic perovskite solar cells (PSCs) have delivered the highest power conversion efficiency (PCE) of 25.7% currently, but they are unfortunately limited by several key issues, such as inferior humid and thermal stability, significantly retarding their widespread application. To tackle the instability issue, all-inorganic PSCs have attracted increasing interest due to superior structural, humid and high-temperature stability to their organic-inorganic counterparts. Nevertheless, all-inorganic PSCs with typical CsPbIBr2 perovskite as light absorbers suffer from much inferior PCEs to those of organic-inorganic PSCs. Functional doping is regarded as a simple and useful strategy to improve the PCEs of CsPbIBr2-based all-inorganic PSCs. Herein, we report a monovalent copper cation (Cu+)-doping strategy to boost the performance of CsPbIBr2-based PSCs by increasing the grain sizes and improving the CsPbIBr2 film quality, reducing the defect density, inhibiting the carrier recombination and constructing proper energy level alignment. Consequently, the device with optimized Cu+-doping concentration generates a much better PCE of 9.11% than the pristine cell (7.24%). Moreover, the Cu+ doping also remarkably enhances the humid and thermal durability of CsPbIBr2-based PSCs with suppressed hysteresis. The current study provides a simple and useful strategy to enhance the PCE and the durability of CsPbIBr2-based PSCs, which can promote the practical application of perovskite photovoltaics.